Lavender or self-blue refers to a

plumage Plumage ( "feather") is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, ...

color pattern in the

chicken The chicken (''Gallus gallus domesticus'') is a domestication, domesticated junglefowl species, with attributes of wild species such as the grey junglefowl, grey and the Ceylon junglefowl that are originally from Southeastern Asia. Rooster ...

(''Gallus gallus domesticus'') characterized by a uniform, pale bluish grey color across all feathers. The distinctive color is caused by the action of an autosomal recessive gene, commonly designated as "''lav''", which reduces the expression of

eumelanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino ...

and

phaeomelanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amin ...

so that black areas of the

appear pale grey instead, and red areas appear a pale buff.Crawford, Roy ''Poultry Breeding and Genetics'', Elsevier, 1990

Description

The "lavender" gene (''lav'') in the chicken causes the dilution of both black (eumelanin) and red/brown (phaeomelanin) pigments, so according to color background, dilution due to "lavender" gives a sort of

color patterns: On an extended black background, this condition causes the entire surface of the body an even shade of light slaty blue, which is the typical phenotype known as '"self-blue"'. On a red/brown color

background, lavender gene degrades color to beige, like in some Pekin Bantams as in the picture set aside. On the color background of the Belgian Bearded d'Uccle Bantams, frequently referred to as the "Mille Fleur" in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

, lavender causes the pattern known as "porcelain". The resulting "porcelain" pattern is beige with each feather tipped with a V-shaped of slaty blue near the end of the feather and the feather tipped with a V-shaped white spangle. Light and

electron microscope An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a ...

studies have revealed that, although lavender

melanocyte Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale) of the skin's epidermis, the middle layer of the eye (the uvea), the inner ear, vaginal epithelium, meninges, bones, and hear ...

s possess relatively normal dendrite morphology, there is defective peripheral accumulation of

melanosome A melanosome is an organelle found in animal cells and is the site for synthesis, storage and transport of melanin, the most common light-absorbing pigment found in the animal kingdom. Melanosomes are responsible for color and photoprotection i ...

s to the dendrites. This results in the patchy transfer of

s into the

keratinocyte Keratinocytes are the primary type of cell found in the epidermis, the outermost layer of the skin. In humans, they constitute 90% of epidermal skin cells. Basal cells in the basal layer (''stratum basale'') of the skin are sometimes referred ...

s of the growing feather. The dilution effect is essentially the result of a mixture of pigmented and unpigmented regions within the feather barbs.

History

The lavender gene was first discovered in the Porcelain variety of Belgian Bearded d'Uccle bantams in 1972,Brumbaugh JA, Chatterjee G, Hollander WF: Adendritic melanocytes: a mutation in linkage group II of the fowl. J Hered 1972, 63:19-25. and verified in 1980. Porcelain colored d'Uccle bantams were around as early as 1909, though the Porcelain variety was not recognized by the

American Poultry Association The American Poultry Association (APA) is the oldest poultry organization in the North America. It was founded in 1873, and incorporated in Indiana in 1932. The first American poultry show was held in 1849, and the APA was later formed in resp ...

until 1964. Whether from the Porcelain d'Uccle or other, unknown sources, the lavender gene has been introduced to a number of new chicken breeds over the years, including the

Polish Polish may refer to: * Anything from or related to Poland, a country in Europe * Polish language * Poles, people from Poland or of Polish descent * Polish chicken *Polish brothers (Mark Polish and Michael Polish, born 1970), American twin screenwr ...

and the Silkie.

Genetic studies

"Lavender" is an

autosomal recessive In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and ...

mutation of the chicken affecting the

neural crest Neural crest cells are a temporary group of cells unique to vertebrates that arise from the embryonic ectoderm germ layer, and in turn give rise to a diverse cell lineage—including melanocytes, craniofacial cartilage and bone, smooth muscle, ...

derived

s. It causes the dilution of both

and

to a light grey or buff, respectively. It has been assigned the symbol ''lav''.Somes, R. G. 1981 ''International Registry of Poultry Genetic Stocks. A Directory of Specialized Lines and Strains, Mutations, Breeds and Varieties of Chickens, Japanese Quail and Turkeys''. Storrs Agricultural Experiment Station, The University of Connecticut, Storrs, Bulletin #460. The ultimate goal of the modern genetic studies is to find out the underlying genes involved in these traits. Lavender in chickens has been found to be a mutation caused by a single base-pair change in

exon An exon is any part of a gene that will form a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term ''exon'' refers to both the DNA sequence within a gene and to the corresponding sequenc ...

1 of MLPH (melanophilin) gene.Vaez, M., Follett, S.A., Bed’hom, B., Gourichon, D., Tixier-Boichard, M., Burke, T. 2008 A single point mutation within the melanophilin gene causes the lavender plumage colour dilution phenotype in the chicken. BMC Genet. 9:7. In genetic linkage studies, ''Lav'' locus has been assigned to a linkage group known as Cp-R-U group (Creeper-Rose comb-Uropygial) . Although Lavender locus is linked to the R (rose comb) locus by 32.5%, its position has not yet mapped.,

Homologous mutations in other species

Until now, all the reported causal mutations in MLPH (melanophilin) of humans, mice and other species have been single-base substitutions or small deletions, the effects of which were limited to the dilution of hairMénasché, G., Ho, C.H., Sanal, O., Feldmann, J., Tezcan, I., Ersoy, F., Houdusse, A., Fischer, A., de Saint Basile, G. 2003 Griscelli syndrome restricted to hypopigmentation results from a melanophilin defect (GS3) or a MYO5A F-exon deletion (GS1). J. Clin. Invest. 112:450-456. or feather colour. The MLPH-associated dilution of coat or

pigmentation should then result in the defective transport of

s. This produces a diluted, leaden or lavender blue-grey colour and has been reported in several mammals: humans ( Griscelli syndrome type 3), mice, cats, dogs and minks

In Japanese quail

The lavender phenotype in

Japanese quail The Japanese quail (''Coturnix japonica''), also known as the coturnix quail, is a species of Old World quail found in East Asia. First considered a subspecies of the common quail, it is now considered as a separate species. The Japanese quai ...

(''Coturnix coturnix japonica'') is a dilution of both eumelanin and phaeomelanin in feathers that produces a blue-grey colour on a wild-type feather pattern background. Studies of intergeneric hybridization proved that the lavender mutation in quail is homologous to the same phenotype in chicken In this species, the lavender phenotype is associated with a non-lethal complex mutation involving three consecutive overlapping chromosomal changes (two inversions and one deletion) that have consequences on the genomic organization of four genes (MLPH and the neighbouring PRLH, RAB17 and LRRFIP1). The deletion of PRLH has no effect on the level of circulating prolactin. Lavender birds have lighter body weight, lower body temperature and increased feed consumption and residual feed intake than wild-type

quail, indicating that this complex mutation is affecting the metabolism and the regulation of

homeothermy Homeothermy, homothermy or homoiothermy is thermoregulation that maintains a stable internal body temperature regardless of external influence. This internal body temperature is often, though not necessarily, higher than the immediate environmen ...

In other bird species

In other bird species, similar feather colour dilutions have been described, including the autosomal recessive slate turkey ('' Meleagris gallopavo''), milky pigeon ('' Columba livia''), and the lavender muscovy duck ('' Cairina moschata''). It is as yet unknown which genes are responsible for these dilution mutations in these bird species.

Chicken breeds with "lavender" varieties

Araucana The Araucana ( es, Gallina Mapuche, italic=no) is a breed of domestic chicken from Chile. Its name derives from the Araucanía region of Chile where it is believed to have originated. It lays blue-shelled eggs, one of very few breeds that do so. ...

* Belgian Bearded d'Anvers (Self-blue and Porcelain phases) * Belgian Bearded d'Uccle Bantam * Belgian d'Everberg *

Booted Bantam , country = , distribution = , standard = , use = show , apa = feather legged , aba = , ee = yes , pcgb = rare true bantam , maleweight = maximum 850 g , femaleweight = m ...

(also called Dutch Booted Bantam) * Dutch Bantam * Old English Game Bantam *

Orpington Orpington is a town and area in south east London, England, within the London Borough of Bromley. It is 13.4 miles (21.6 km) south east of Charing Cross. On the south-eastern edge of the Greater London Built-up Area, it is south of St Mary ...

* Pekin (chicken) *

Silkie Bantam The Silkie (also known as the Silky or Chinese silk chicken) is a breed of chicken named for its atypically fluffy plumage, which is said to feel like silk and satin. The breed has several other unusual qualities, such as black skin and bones, ...

* Wyandottes, in the UK as recently as 2014

References

{{Reflist, 30em

External links

American Belgian d'Uccle Bantam Club
Chicken plumage patterns Bird colours